iso-, is-
(Greek: equal; by extension: same, similar, alike; normally used as a prefix)
Used in numerous terms, nearly all scientific; denoting: equality, similarity, uniformity, or identity; the second element being properly and usually of Greek origin, rarely of Latin [the proper prefix in the latter case being equi-]. In biology, denoting for or from different individuals of the same species). For a large list of iso- opposites or antonyms, see aniso-.